Hi,
I've found a way to replace GNOME's volume control with PA's volume control.
I've used gnome-wm as basis and created /apps/gnome-volume-control/rh/volume_control key in GConf.
Also, there's needed to rename %{_bindir}/gnome-volume-control by adding ".real" suffix. It still works ;) .
I'm attaching a script to put in %{_bindir}/ and schema to put in %{_sysconfdir}/gconf/schemas/gnome-volume-control.schemas (by editing file and pasting XML tree).